Oscillograph apparatus



April 19, 1949.

H. s'. LASHER, JR

OSCILLOGRAPH APPARATUS Filed July 23, 1945 1%. a MM 5 0 fm 5M mH .m .H

Patented Apr. 19, 1949 OSCILLOGBAPH APPARATUS Hiram S. Lasher, Jr.,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York Application July 23, 1945, Serial No. 606,513

13 Claims.

1 My invention relates to apparatus for analyzing electric oscillations,and more particularly to cathode ray oscillographs of the type known assynchroscopes. Such instruments are commonly used for analysis ofrecurrent electric impulses of very short duration, such as thoseemployed in radio detection and direction finding equipment, and thelike.

It is a general object of my invention to provide a new and improvedcathode ray oscillograph apparatus including means for synchronizing theoperation of a source of oscillations to be observed or analyzed withthe timing sweep of the electron beam.

It is a still further object of my invention to provide a new andimproved cathode ray oscillograph apparatus in which a single source oftiming oscillations synchronously controls the sweep of an electronbeam, the intensity of the beam, and the trigger circuit controlling thesource of oscillations to be analyzed. It is a still further object ofmy invention to provide, in an apparatus of the above character, noveland simple means whereby the source of timing oscillations may bedisabled and the source of observed oscillations itself usedsynchronously to control the beam sweep and beam intensity when thesource of observed oscillations is of an inherently recurrent character.

It is a more particular object of my invention to provide, in asynchroscope of the above type, an organization of timing andsynchronizing circuits having such interrelated characteristics that itis equally reliable and eificient over a very Wide band of frequenciesand. capable of analyzing pulses of much shorter duration than haveheretofore been observable with an instrument of this general type.

My invention itself, together with further objects and advantagesthereof, will be more fully understood by referring now to the followingdetailed specification taken in conjunction with the accompanyingdrawing, the single figure of which is a schematic circuit diagram of acathode ray oscillograph apparatus embodying my invention.

Referring now to the drawing, I have shown my invention applied to asynchroscope apparatus comprising a cathode ray discharge device l,source 2 of electric impulses or oscillations to be observed, and asource 3 of substantially constant frequency sinusoidal oscillations forcontrolling the sweep and intensity of the electron beam andsynchronizing the operation of the source 2 with the beam sweep.

The source of sine wave voltage 3 may be an oscillator of any Well-knowntype, such as a crystal or resonant circuit oscillator, and preferablyincludes suitable means, such as variable capacitors, inductors, or thelike, controlled by a dial d for varying the frequency of the generatedoscillations. The sine wave oscillations of selectabl constant frequencyfrom the source 3 are amplified in an electron discharge device 5 andsupplied to a phase shifting circuit 6 connected to the secondarywinding 1 of a transformer 8, the primary winding 9 of which isconnected in the anode circuit of the amplifier 5.

The phase shifting circuit 6 comprises a capacitor til, an inductor H,and a variable resistor l2. A two-position selector switch I3 isarranged alternatively to connect either the capacitor H] or theinductor II in series with the resistor [2 across the terminals of thetransformer winding 1. The mid-point of the transformer winding 1 isconnected to ground. From opposite terminals of the variable resistorl2, sine wave oscillations of controllable phase relation are derived.The phase shift results from the reactive characteristics of thereactors l0 and H, and is controlled by the resistor I2. It will beevident that the phase of the oscillations supplied from the lowerterminal of the resistor I2 is the same as that appearing at the lowerterminal of the transformer winding 1, since these points arepermanently and directly connected. The relative phase of theoscillations at the upper terminal of the resistor i2 is variable. Itwill be evident that, when the resistance of the resistor I2 is reducedsubstantially to zero, the oscillations at the upper terminal of theresistor are substantially in phase with those at the lower terminal. Asthe resistor I2 is inserted in the circuit with the capacitor l0connected in series therewith, the oscillations at the upper resistorterminal are caused progressively to lag the fixed oscillations at thelower terminal. Similarly, if the inductor ll is in circuit, insertionof the resistor 52 causes the oscillations at the upper resistorterminal to lead the fixed oscillations at the lower terminal. By thisphase shifting circuit, it is possible to displace the relative phase ofthe fixed and variable oscillations over a range of substantially Itwill be understood, of course, that the range of phase displacement islimited at its extremities by the finite values of the circuitimpedances. If desired, these end ranges of phase displacement may becovered by reversing the output connections from the upper and lowerterminals of the variable resistor 12 so that substantially 360 phaseshift is possible.

The fixed phase oscillations from the lower terminal of the resistor Hare used to control a beam sweep generator and intensifier in a mannerto be more fully described hereinafter. The negative half cycles of thevariable phase oscillations from the upper terminal of the resistor l2are supplied through a resistor Ma and a diode M in series to the inputcircuit of an electron discharge device l and are utilized to generatetriggering pulses for control of the source 2 of oscillations to beobserved. The resistor 14a is shunted by a capacitor 14b. The diode l4prevents loading of the phase shifting circuit on positive half cyclesand consequent unbalance of the phase shifting network. It will beunderstood that the normal function of the phase shifting circuit 6 isto displace in time the triggering of the source 2 with respect to theinitiation of the beam sweep so that the observed phenomenon may be madeto appear at any desired time on the beam sweep. In this way, theleading edge of pulses or other oscillations from the source 2 is notlost in its representation on the cathode ray screen.

The trigger circuit comprises a pair of electron discharge devices l5and I 6 for amplifying and sharpening the sine wave oscillationssupplied from the variable phase terminal of the phase shifting circuit6 and a second pair of electron discharge devices I! and I8 connected asa blocklng oscillator to supply to an output transformer [9 a series ofsubstantially rectangular pulses of short duration having theperiodicity of the timin source 3.

The discharge device I5 comprises an anode 2!) connected to a suitablesource of positive unidirectional supply B+ through an anode resistor 2|and inductor 2 la, a cathode 22 connected directly to ground, and acontrol electrode 23 connected to the upper terminal of the phaseshifting resistor 12 through the diode I4 and resistor Ma. The controlelectrode 23 is connected to ground through a grid resistor 24.Oscillations appearing upon the anode 20 of the discharge device [5 aresupplied through a coupling capacitor 25 to a control electrode 26 ofthe discharge device IS. The

discharge device 16 includes also an anode 21 connected to 13+ throughan anode resistor 28' and a cathode 29 connected directly to ground. Thecontrol electrode 26 is biased negative with respect to the cathode 29by connection through a grid resistor 30 to a suitable source ofnegative unidirectional potential 3-. The potential source 3- isby-passed by a capacitor 3i.

In operation, the blockin oscillator trigger circuit comprising thedischarge devices I5 and I6 functions in the following manner. Thedischarge device IE is normally conductive and the discharge device I 6is normally non-conductive. Negative half waves supplied from thephaseshifting circuit 6 to the input electrode 23 of the dischargedevice 15 periodically render the discharge device l5 non-conductivethereby to raise the potential of its anode 20 so that positive pulsesof substantially sinusoidal configuration are supplied through thecoupling capacitor 25 to the input electrode 26 of the discharge deviceIS. The discharge device l6, normally cut ofi because of its negativebias, is periodically rendered conductive and driven to saturation bythe positive input pulses, so that fiat-topped negative pulses appear atthe anode 21 of the discharge device l6 as indicated upon the drawing.These negative pulses are supplied through a coupling capacitor 32 to aregenerative blocking oscillator comprising the discharge devices I! andHi.

The discharge device ll of the blocking oscillator comprises an anode 33connected to B+ through a pair of inductors 34a and 341), a cathode 35connected directly to ground, and a control electrode 36 biased beyondcutoif by connection through a resistor 3! to a suitable source ofnegative unidirectional potential 3-. The B- potential source isby-passed by a capacitor 38. The inductor 34b is shunted by a resistor tl-c. The control electrode 36 is regeneratively coupled to the anode 33and, thus, to the anode 21 of the discharge device It through atransformer 39 having a primary winding ll) and a secondary winding 4 lOne terminal of the primary winding 40 is connected to ground and theother terminal is connected through a couplin capacitor 42 to the anode33. The secondary Winding ll is connected at one end to the controlelectrode 36 through a coupling capacitor t3 and at the other end to asource of negative unidirectional potential 13-. The potential source 3-is by-passed by a capacitor Ml.

The other oscillator discharge device l8 comprises an anode 45 connectedto B+ through a primary winding 46 of the output transformer IS, acathode 41 connected directly to ground, and a control electrode 58. Thecontrol electrode 48 is connected to the control electrode 36 of thedischarge device I'! through the coupling capacitor 43. Thus, byconnection through the transformer winding 4 I, the control electrode l8 is biased negative with respect to the cathode 11 from the B potentialsource.

In operation, the blocking oscillator comprising the discharge devicesll and 58 functions in the following manner. Negative pulses from theanode of the discharge device l6 are supplied through the couplingcapacitors 32 and 2 to the primary winding 40 of the transformer 39. Thetransformer windings are so disposed that, when the ungrounded terminalof the transformer primary winding 49 is thus driven negative, apositive voltage pulse is impressed upon the control electrodes 36 and38 from the secondary winding 4| of'the transformer. Both dischargedevices I! and I8 are normally cut off by reason of their negative biaspotentials. As soon as such a positive grid pulse is impressed upon thetubes, however, both tubes become conducting. By regenerative actionthrough the transformer 39 and the device H, the grids 36 and 48 arerapidly driven to a high positive potential, so that both dischargedevices are driven to saturation. It will be clear that, as soon as thedischarge device I! begins to conduct so that the anode 33 falls inpotential, a further negative potential is impressed upon the ungroundedterminal of the transformer winding 40 so that the grids 36 and 53 aredriven even further positive. Thus, once conduction has been initiatedin the discharge device H by imposition of a negative triggering pulseupon the transformer winding ll], the grid potential of both dischargedevices 5'5 and i8 is rapidly built up to a high positive value byregeneration through the transformer 39 and the discharge device 11. Thepulse duration is determined by the time constant of a grid dischargecircuit including the capacitor 43 and the grid to cathode resistance ofthe tube l7. As soon as the grid potential decays to a predeterminedpoint with capacitive discharge through the grid circuit the anodecurrent of the device ill decreases slightly and initiates degenerativeaction through the discharge device I! and the transformer39. Thedegenerative action effects a very rapid termination of discharge inboth the discharge devices ll and I8. Thus, by saturation limiting, thecurrent pulse through the discharge device It and the output transformerI9 is substantially rectangular in configuration. This rectangular pulseis supplied through a trigger lead at and a contact 523 of a controlswitch 5| to trigger the external source 2. While the function of theselector switch 55 will be more :fully described hereinafter, it will beunderstood that the switch 5D is closed, as shown, only when the source2 requires triggering for impulse generation.

The output impulses from the external source 2 are in all cases suppliedthrough a lead 52 to the vertical deflection plates 53 of the cathoderay discharge device I.

Referring now to the cathode ray sweep circuit, it will be recalled thatthis circuit is controlled by the fixed phase oscillations derived fromthe lower terminal of the phase shifting resistor 12 and difiering inphase with respect to the oscillations from the upper resistor terminalutilized to control the trigger circuit described above. As shown on thedrawings, fixed phase oscillations are supplied from the phase shiftingcircuit 6 through a resistor 55 and a diode 56 to the input circuit ofan electron discharge device 5?. The resistor 55 is shunted by acapacitor 55a. The discharge device 51 comprises an anode 53, a controlelectrode 59, and a cathode t9, and, together with an electron dischargedevice 6!, constitutes a blocking oscillator trigger circuit similar tothat described above in connection with the discharge devices |5 and I6.Accordingly, the discharge device 6| comprises an anode 62, a cathode62-3, and a control electrode 65. The anode 58 is connected to asuitable source of positive potential B+ through an anode resistor 65and inductor 65a. The anode 62 is connected to 13+ through a resistor 66and the cathodes 60 and 5| are connected directly to ground. The controlelectrode 59 of the discharge device 51 is connected to ground by a gridresistor 61. The control electrode 64 of the discharge device 6| isbiased negative with respect to the cathode by connection through aresistor 68 to a suitable source of unidirectional negative potential B.The source 3- is by-passed by a capacitor 59. The anode output of thedischarge device 51 is coupled through a coupling capacitor NJ to thecontrol electrode 64 of the discharge device (5|, thereby periodicallyto render the discharge device 5| conductive. Accordingly, recurrentnegative voltage pulses, limited in amplitude by saturation, appear uponthe anode 62 in the manner heretofore described in connection with theanode 21 of the discharge device IS.

The negative pulses appearing upon the anode 62 of the discharge device6| are supplied through a coupling capacitor H to trigger a blockingoscillator circuit comprising a pair of electron discharge devices '|2and 13. This blocking oscillator is similar in all respects to theregenerative blocking oscillator described above in connection with thedischarge devices I! and Hi, so that a description of its operation neednot be repeated. vIt should be noted, however, that the output dischargedevice 13 has its anode la connected to 3+ through a load resistor 15rather than a transformer, while a control electrode it of the device'13 is connected to the regenerative grid transformer 11 through acontact 18 on the selector switch 5|. Thus, the output from the blockingswitch 5| has two alternative positions in one of which the controlelectrode 16 is connected to the grid transformer l1 and in the other ofwhich the control electrode 16 is connected directly to a negative biassource B- through a resistor 79 and to the output of the externalimpulse source 2 through a coupling capacitor 85, an amplifier andinverter 8|, and a contact 82 of the switch 5|. The purpose of theswitch contacts l3 and 82 in connecting the control electrode it to theoutput lead 52 from the source 2 will be described in more detailhereinafter. An inverter is used only when the observed signal isnegative.

Negative output pulses from the oscillator comprising the dischargedevices l2 and 73 are supplied from the anode 14 of the device it totrigger an aperiodic multivibrator circuit comprising a pair of electrondischarge devices 83 and 84. The discharge device 83 comprises an anode85 connected to 3+ through the anode resistor 15, a cathode 86 connecteddirectly to ground, and a plurality of control electrodes 87, 88 and 89.The control electrode Bl is a suppressor electrode connected directly tothe cathode in the usual manner. The control electrode 88 is a screenelectrode which is maintained at a substantially constant positivepotential by means of a potential divider comprising a resistor 9i)connected in series with a voltage regulating gaseous discharge tube 9|between B+ and ground, the control electrode 88 being connected to thecommon terminal of the resistor 90 and the voltage regulating tube 9!.The control electrode 89 is connected to a negative bias source B-through a grid resistor 92 and to the anode 93 of the discharge device84 through a coupling capacitor 94 shunted by a resistor 95. Thedischarge device 841 comprises also a cathode 96 connected directly toground and a control electrode 91 which is biased positive by connectionthrough a resistor 98 to the potential source B+. The control electrode97 is also coupled to the anode 85 of the discharge device 83 throughany desired one of a plurality of selectable coupling capacitors 99,99a, 9%, or 990. The desired capacitor 99 is selected by a switchcontact IE5 on a gang selector switch I I3 to be more fully describedhereinafter. The anode 93 of the discharge device 84 is also connectedto B+ through an anode resistor 93a.

In the operation of the pulse forming multivibrator comprising thedischarge devices 83 and 84, the discharge device 83 is normallynon-conductive by reason of the negative bias potential on the electrode89, and the discharge device 84 is normally conductive because of thepositive bias on its control electrode. Negative triggering impulsesfrom the anode 14 of the oscillator tube T3 are impressed through theselected coupling capacitor 99 upon the control electrode 9? of thedischarge device 84. Due to the regenerative characteristics of thetriggering oscillator comprising the discharge devices 12 and 73, thistriggering impulse has a very sharp leading edge. As soon as the controlelectrode 97 is thus driven negative, the discharge device 84 is cut on,so that its anode potential increases abruptly. Upon increase in thepotential of the anode 93, a positive potential is impressed upon thecontrol electrode 89 of the device 83 through the coupling resistor 95and capacitor 94. The capacitor 94, connected in shunt with the resistor95, prevents attenuation of the sharp leading edge of the positive pulseimpressed upon the control electrode 89. When the control electrode 89is driven in a positive direction, the discharge device 83 is renderedconductive, so that its anode 85 draws a load current through the anoderesistor I and the anode becomes less positive in potential. The reducedpositive potential at the anode 85 drives the control electrode 9'! ofthe device 84 further negative, thereby further to increase the positivepotential of the control electrode 89 through the coupling resistor 95and capacitor 94. This regenerative action now proceeds independently ofthe triggering pulse initiated at the anode I4 of the device I3, so thatthe anode 85 of the device 83 is driven rapidly to its minimum potentialin a time determined by the regenerative characteristics of themultivibrator circuit. When the discharge device 83 reaches saturation,the regenerative action ceases.

The resistor 98 and the selected capacitor 99 connected in seriesbetween 3+ and the anode 85 of the discharge device 83 constitute atiming circuit determining the switching time of the multivibrator tube,When regeneration in the multivibrator ceases the capacitor 99 ischarged to the potential across the resistor I5 thereby gradually toincrease the potential of the control electrode 91 in a positivedirection along an eX- ponential curve determined by the time constantof the circuit 98, 99. The anode 85 of the device 83 remains at itsmaximum negative potential until the control electrode 91 increases inpotential sufiiciently to render the discharge device 84 againconductive. When such conduction takes place, the anode 93 of the device84 experiences a sudden drop in potential thereby to impress upon thecontrol electrode 89 of the device 83 a negative potential through thecoupling elements 94, 95. The negative potential upon the controlelectrode 89 reduces conduction of the discharge device 83, thereby toincrease the potential of the anode 85 and initiate degeneration betweenthe discharge devices 83 and 84. The negative pulse at the anode 85 isthus abruptly terminated. The initial condition is thereforere-established with the discharge device 83 nonconductive and device 84conductive. The multivibrator circuit remains in this condition untilinitiation of the next triggerin impulse at the oscillator tube anodeI4.

It will now be observed that the combination of the regenerativetriggering oscillator comprising the devices 12 and 13 with theregenerative multivibrator comprising the devices 83 and 84 produces atthe anode 85 of the device 83 a negative pulse having a very sharplysloped leading edge,

'the shape at the initiation of the leading edge resulting fromoscillator regeneration, and the higher voltage portion of the pulsebeing determined by the regenerative multivibrator characteristics.

The negative pulses thus appearing at the anode 85 of the multivibratordevice 83 are supplied through a diode I8I to the anode I82 of a sweepgenerating discharge device I 83, The discharge device I83 comprises, inaddition to the anode I82, a cathode I84 connected to ground through acathode bias resistor I85, a control electrode I88 connected directly toground, a suppressor electrode I81 connected directly to the cathodeI84, and a regulated screen grid electrode I88. The

screen grid I88 is maintained at a substantially constant positivepotential by connection to the common terminal of a resistor I89 and avoltage regulating tube II8 connected in series circuit relation as avoltage divider between 3+ and ground. Thus, it will be seen that thedischarge device I83 is normally connected between 13+ and groundthrough the anode resistor I5 and the diode I8I, so that the anodesupply potential to the discharge device I83 is recurrently interruptedfor the duration of the negative multivibrator pulses appearing upon theanode 85 of the discharge device 83.

The sweep generating discharge device I83 and cathode resistor I85 areshunted by any desired one of a plurality of selectable capacitors III,IIIa, lb, and Mic. The desired capacitor III may be selected by acontact I I 2 on the manually operable selector switch H3. The capacitorII I c is shown in dotted lines because physically it represents onlythe distributed and stray capacitance of the circuits involved, theswitch contact actually being left unconnected to any physicallyrealizable circuit element.

In operation, the sweep generating discharge device I83, when connectedthrough the diode I8I to the supply source 3+, is normally conductiveand impresses upon the selected capacitor III a charge equal to thevoltage drop between the anode I82 and ground. Recurrently, and for theshort duration of the recurrent multivibrator pulses, the anode supplysource is removed from the discharge device I83 by reason of the factthat, for the duration of these pulses, the diode I 8| is renderednon-conductive. During such periods, the charge accumulated upon theselected capacitor III is dissipated through the discharge device I83thereby to form a saw-tooth wave which is utilized to control thehorizontal sweep of the cathode ray beam, The saw-tooth voltage acrossthe selected capacitor III is coupled to the horizontal plates II4 ofthe cathode ray discharge device I through a coupling capacitor II5. Asimilar sweep circuit is disclosed and claimed in copending applicationSerial No. 563,928, filed November 17, 1944, issued September 21, 1948,as Patent 2,449,801, by Frank J. Bias and Harold W. Lord, and assignedto the same assignee as the instant application.

During the period of the beam sweep, the cathode ray is intensified by acircuit associated with the multivibrator output at the anode of thedischarge device 83. This circuit comprises an electron discharge deviceI28 having an anode I2I connected to 3+ through a load resistor I22, acathode I23 connected to ground through a cathode bias resistor I24, anda plurality of control electrodes I25, I26 and I21. The screen andsuppressor electrodes I26 and I25, respectively, are connected togetherand to 3+ through a resistor I28. The control electrode I21 is connectedto ground through one of a plurality of grid resistors I29, I29a, I291),or I290. The connection of the resistors I29 is controlled by a contactI38 on the selector switch H3. The control electrode I2! is also coupledto the anode 85 of the multivibrator discharge device 83 through aresistor I3I and a capacitor I 32.

In operation, the intensifier discharge device I28 is normallyconductive by reason of the low bias on its control electrode I21.However, upon the occurrence of a negative multivibrator pulse at theanode 85, a negative impulse is transferred to the control electrode I21of the discharge device I28 through the coupling capacitor I32. Thisnegative impulse cuts off the discharge device I20, thereby to increaseits anode potential. The discharge device I29 remains out 01f for alength of time determined by the time constant of the circuit comprisingthe capacitor I32, the resistor I3I, and a selected resistor I29. Thepositive impulse appearing upon the anode I2l of the discharge deviceI29 is impressed upon a control electrode I33 of the cathode raydischarge device I through a coupling capacitor I39, thereby tointensify the cathode ray beam.

The remaining circuits of the cathode ray discharge device I areconventional. The discharge device I is provided with a cathode I35connected directly to ground and an anode I36 coupled to the positiveterminal of a battery I31, the negative terminal of which is grounded.Negative grid bias for the control electrode I33 is provided by abattery I38 connected in series with a resistor I39 between the controlelectrode I33 and ground.

It will be noted that the selector switch II3 is a gang switch arrangedsimultaneously to control the capacitors 99, the capacitors I l I, andthe resistors I29. This switch controls the sweep time of the cathoderay tube. It will be recalled that the capacitors 99 control theduration of the multivibrator pulse appearing upon the anode B of thedischarge device 33. It is for the dura tion of this pulse, as thusdetermined, that anode voltage is removed from the sweep dischargedevice II33. Accordingly, therefore, the proper capacitor III isselected in accordance with the value of the desired capacitor 99 togenerate a sweep pulse of the same duration as the multi- Vibtratorpulse. Similarly, the resistor I129 is selected so that the timeconstant of the grid intensifier circuit is so adjusted that theintensifier pulse has a duration substantially equal to the duration ofthe sweep.

The switch 5| is provided in order selectively to allow for eithertriggered operation or servo operation of the cathode ray apparatus.Triggered operation is used when the source 2 of oscillations orimpulses to be observed is aperiodic or has no inherent repetition rate,but must be triggered to initiate each outlet pulse. The switch 5| isshown in position for the latter operation. If, however, the externalsource 2 is a generator of a type having an inherent repetition rate ofits own, the trigger circuit coupled to the source 2 through the lead 49cannot be used. In this case the cathode ray apparatus is operatedservo, whereby the external source 2 itself controls the sweep andintensifier circuits. For this operation, it will be observed that thecontact 59 of the switch 5i disconnects the trigger lead 49 from theexternal source 2 and that the output of the source 2 is substituted forthe blocking oscillator 72 as the sweep multivibrator trigger. Thisservo trigger circuit may be followed from the output lead 52 of thesource 2 through the contact 92 of the switch 5!, the amplifier andinverter Bl, the blocking capacitor 89, and the contact iii of theswitch 5| to the control electrode I6 of the discharge device I3.

It will now be evident from the foregoing that I have provided a veryversatile improved synchroscope apparatus which is operable with equalefiiciency over a wide range of repetition rates and is capable ofreproducing on its screen pulses of very short duration. For example, intriggered operation, I have found that my apparatus is capable offunctioning with equal facility at repetition rates varying from 60cycles persecond to 140 kilocycles per second and at sweep speedsranging from as low as about one-thirtieth microsecond per inch to ashigh as 6 micro-seconds per inch. Even higher sweep speeds may besecured by utilizing other high speed triggered sweep generators knownto the art. It will be recalled that the pulse at anode of device 83 hasa very sharply sloped leading edge, so this pulse may be used directlyas a very high speed sweep if desired. In any case, the system isadiusted to operate so that the necessary rapid sweep impulses arederived from the fixed phase output of the phase shifter 6 at arepetition rate determined by the selected frequency of the oscillater3, and the intensifier circuit intensifies the cathode ray beam in exactsynchronism with the sweep impulses. Also, in such operation, anaperiodic external source of oscillations 2 is controlled by a triggerimpulse derived from the variable phase output of the phase shifter 6.The phase variation of the trigger pulse with respect to the initiationof the sweep is readily controllable over a wide range of phase angles,so that the triggered impulse may be made to appear at any desired pointin the sweep of the beam. In actual operation, I have found that myphase shifting phase circuit 6, especially when combined with areversing switch as heretofore suggested, is capable of varying therelative phase of sweep and trigger impulses over substantially 360".

By way of illustration of one application of my invention, I have shownupon a fluorescent screen l lo associated with the cathode ray tube I atypical picture which may appear in the event that the oscillationsource 2 is a radio direction and range finding apparatus of the typecomprising a pulse transmitter and a receiver of echo or reflectedpulses. In accordance with my invention, the cathode ray beam is turnedon once per cycle of the oscillations from the timing source 3. Thehorizontal sweep of the beam' traces a line Hil upon the fluorescentscreen I40. synchronously with the initiation of the beam sweep and infixed time delay relation with respect thereto, as determined by thephase shifting circuit 6, triggering impulses are supplied to the source2 through the triggering circuit terminating in the lead 49, thereby torender the transmitter operative. Upon triggering of the transmitter, atransmitted pulse I42 appears upon the fluorescent screen M9 byoperation of the source 2 and the vertical deflection plates 53. In theevent that the pulse I42 encounters a detected object and is reflectedback to the receiver of the source 2, a reflected pulse I43 will appearupon the fluorescent screen it a predetermined time after the pulse I42,as determined by the distanc between the source 2 and the reflectingobject. In this manner, the range of a reflecting object may bedetermined.

Certain features of the synchronizing system herein described areclaimed in their broader aspects in the foregoing application of Biasand Lord, Serial No. 563,920, filed November 17, 1944.

While I have shown and described only a preferred embodiment of myinvention, many modifications will occur to those skilled in the art andI therefore wish to have it understood that I intend in th appendedclaims to cover all such modifications as fall within the true spiritand scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

' 1. An apparatus for analyzing electric oscillations comprising meansfor projecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source oftiming oscillations, a source of observed oscillations connected to oneof said deflecting elements, phase shifting means for deriving from saidtiming source fixed and variable phase electric oscillations, meansutilizing said fixed phase oscillations and the other of said deflectingelements recurrently to sweep said beam across said surface, and meansutilizing said variable phase oscillations synchronously to control saidsource of observed oscillations.

2. An apparatus for analyzing electric oscillations comprising means forprojecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source oftiming oscillations, a source of observed oscillations connected to oneof said deflecting elements, phase shifting means for deriving from saidtiming source fixed and Variable phase electric oscillations, a pair ofsimilar regenerative pulse forming means for deriving from said fixedand variable phase oscillations substantially rectangular Voltageimpulses of fixed and variable phase relation respectively, meansutilizing said variable phase impulses recurrently to render said sourceof observed oscillations operative, and means including the other ofsaid deflecting elements for utilizing said fixed phase impulsesrecurrently to deflect said beam across said surface in synchronism withoscillations supplied to said first deflecting element from said sourceof observed oscillations.

3. An apparatus for analyzing electric oscillations comprising means forprojecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source oftiming oscillations, a source of observed oscillations connected to oneof said deflecting elements, phase shifting means for deriving from saidtiming source fixed and variable phase electric oscillations, a pair ofsimilar regenerativemeans for deriving from said fixed and variablephase oscillations substantially rectangular recurrent voltage impulsesof fixed and variable phase relation respectively, means utilizing saidvariable phase impulses to control said source of observed oscillations,means for deriving from said fixed phase impulses substantiallysaw-tooth voltage impulses of like duration, and means for impressingsaid saw-tooth impulses upon the other of said deflecting elementsrecurrently to sweep said beam across said screen synchronously with thecontrol of said source of observed oscillations.

4. An apparatus for analyzing electric oscillations comprising means forprojecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source ofoscillations to be observed and a source of substantially saw-toothsweep im-- pulses connected to said coordinate deflecting elementsrespectively, a source of substantially sinusoidal timing oscillations,phase shifting means for deriving from said timing source electricoscillations in fixed and variable time phase relation respectively,separate regenerative pulse forming means utilizing said fixed andvariable phase oscillations to provide series of substantiallyrectangular recurrent electric impulses of fixed and variable time phaserelation respectively, means utilizing said fixed phase impulses tocontrol said source of sweep oscillations, and means utilizing saidvariable phase impulses synchronously to control said source of observedoscillations.

5. An apparatus for analyzing electric oscillations comprising means forprojecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source ofoscillations to be observed and a source of substantially saw-toothsweep impulses connected to said coordinate deflecting elementsrespectively, a source of timing oscillations, phase shifting means forderiving from said timing source electric oscillations in fixed andvariable time phase relation respectively, separate regenerative pulseforming means utilizing said fixed. and variable phase oscillations toprovide series of substantially rectangular periodic electric impulsesof approximately equal duration and of fixed and variable time phaserelation respectively, means utilizing said fixed phase impulses todetermine the periodicity of said sweep impulses, means utilizing saidfixed phase impulses to intensify said beam during the sweep intervals,and means utilizing said variable phase impulses periodically to rendersaid source of observed oscillations operable to deflect said beamsynchronously with the beam sweep.

6. An apparatus for analyzing electric oscillations comprising means forprojecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source ofoscillations to be observed and a source of substantially saw-toothsweep impulses connected to said coordinate deflecting elementsrespectively, a source of timing oscillations, phase shifting means forderiving from said timing oscillations electric oscillations in fixedand variable time phase relation respectively, a pair of similarregenerative pulse forming means utilizing said fixed and variable phaseoscillations to provide series of substantially rectangular periodicelectric impulses of approximately equal duration and of fixed andvariable time phase relation respectively, means utilizing said fixedphase impulses to determine the periodicity of said sweep impulses,pulse forming means utilizing said fixed phase impulses to intensifysaid beam synchronously with the beam sweep, means utilizing saidvariable phase impulses periodically to render said source of observedoscillations operable to deflect said beam synchronously with the beamsweep, and interdependent means for adjusting the duration of said fixedphase impulses, said sweep impulses and said intensifier impulses.

7. An apparatus for analyzing electric oscillations comprising means forprojecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source ofrecurrent impulses to be observed and a source of substantiallysaw-tooth sweep impulses connected to said coordinate de fleetingelements respectively, an aperiodic regenerative pulse forming circuitcoupled to said source of observed impulses and arranged to generate aseries of substantially rectangular electric impulses having apredetermined duration, means utilizing said electric impulses todetermine the periodicity of said sweep impulses, pulse forming meansutilizing said electric impulses to intensify said beam synchronouslywith the beam sweep, and interdependent means for adjusting the durationof said electric impulses, said sweep impulses and said intensifierimpulses.

8. An apparatus for analyzing electric oscillations comprising means forprojecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source ofobserved oscillations connected to one of said deflecting elements,regenerative pulse forming means utilizing said observed oscillations togenerate a series of substantially rectangular recurrent voltageimpulses, and separate pulse forming means utilizing said voltageimpulses recurrently to intensify said beam and synchronously to sweepsaid beam across said surface.

9. An apparatus for analyzing electric oscillations comprising means forprojecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source oftiming oscillations, a source of observed oscillations, a pulse formingnetwork, and means for selectively connecting said timing source andsaid source of observed oscillations to trigger said pulse formingnetwork thereby to generate a series of substantially rectangularrecurrent voltage impulses, and separate pulse forming means utilizingsaid voltage impulses recurrently to intensify said beam andsynchronously to sweep said beam across said surface.

10. An apparatus for analyzing electric oscillations comprising meansfor projecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source oftiming oscillations, a source of observed impulses, an aperiodic pulseforming network, capacitive discharge means triggered by said pulseforming network and connected to one of said deflecting elementsrecurrently to sweep said beam across said surface, separate pulseforming means triggered by said network and arranged recurrently tointensify said beam synchronously with said beam sweep, and switchingmeans arranged selectively to connect said timing source to trigger saidpulse forming network and control said source of observed impulses andto disable said timing source and connect said source of observedimpulses to trigger said network.

11. An apparatus for analyzing electric oscillations comprising meansfor projecting an electron beam against a sensitive surface, a pair ofcoordinate deflecting elements for controlling said beam, a source oftiming oscillations, a source of observed oscillations connected to oneof said deflecting means, phase shifting means for deriving from saidtiming source fixed and variable phase electric oscillations, similarregenerative pulse forming networks for deriving from said fixed andvariable phase oscillations substantially rectangular periodic voltageimpulses of fixed and variable phase relation respectively, aregenerative time element pulse forming network, switching meansarranged selectively to supply said fixed phase impulses and impulsesfrom said source of observed oscillations to trigger said time elementnetwork, said switching means supplying said variable phase impulses totrigger said source of observed oscillations whenever said fixed phaseimpulses trigger said time element network, and means coupled to saidtime element network synchronously to intensify said beam and to sweepsaid beam across said surface.

12. A saw-tooth Wave generator comprisin a source of electric currentsupply, a normally-conductive electron discharge device including ananode and a'cathode connected in circuit with said supply source througha normally-conductive unilateral conducting device and through a loadresistor in series circuit relation, a timing capacitor connected inparallel circuit relation with said discharge device, means for suddenlyreversing the voltage across said unilateral conducting device to permitdischarge of said capacitor through said discharge device, said meanscomprising a second, normally-non-conductive electron discharge deviceincluding an anode and a cathode connected in circuit with said sourcethrough said resistor and also including a control electrode, and meansfor impressing 2. Voltage pulse on said control electrode in a polarityto render said second discharge device conductive for a predeterminedpulse interval.

13. A saw-tooth wave generator comprising a source of electric currentsupply, a normally-conductive electron discharge device having an anodeand a cathode connected in circuit with supply source through anormally-conductive unilateral conducting device and through a loadresistor in series circuit relation, a timing capacitor connected inparallel circuit relation with said discharge device, means for suddenlyreversing the voltage across said unilateral conducting device to permitdischarge of said capacitor through said discharge device, said meanscomprising a second, normally-non-conductive electron discharge deviceincluding an anode and a cathode connected to said source through saidresistor and also including control electrode, means for abruptlyimpressing a pulse on said control electrode to initiate conduction insaid second discharge device, and regenerative time element means forcontrolling and terminating said conduction, thereby to form across saidresistor a substantially rectangular negative voltage pulse ofpredetermined duration.

HIRAM S. LASHER, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,241,256 Gould May 6, 19412,258,752 Fewings et al Oct. 14, 1941 2,286,894 Browne et al June 16,1942 2,368,449 Cook Jan. 30, 1945 2,423,931 Etter July 15, 1947

